Human intraocular fluids are collected during the course of surgery to repair retinal detachment, remove vitreous and strip membranes of proliferative vitreoretinopathy (PVR), and remove vitreous and cataract from uveitic eyes. These fluids (ordinarily discarded) are analyzed for interleukin 1 (IL-1) and interleukin 2 (IL-2) activity by bioassays. Specimens from 88 patients have been analyzed for IL-1. Il-1 activity was found in 90% of uveitic eyes, 35% of eyes with retinal detachment and 17% of eyes with proliferative vitreoretinopathy. Thirty-two specimens have been analyzed for IL-2. Ten percent of uveitis patients, 20% of retinal detachment patients and 60% of PVR patients had detectable IL-2 activity. IL-1 is a mediator in multiple organ-specific pathways. Its presence in the eye suggests a role in intraocular inflammatory and immune processes. IL-2 is produced by activated T cells. The high percentage of PVR patients with IL-2 activity suggests a role of the immune system in proliferative vitreoretinopathy.